The launch of online spin-off Class, following a group of schoolkids in the iconic Coal Hill School that has been a part of Doctor Who since its pilot, could mean a new beginning for the franchise. If it is successful, there's no doubt the BBC will want to make the most of the audience's love for Doctor Who spin-offs. But this isn't the first time that's happened.
Doctor Who pulled an 'Avengers' in the same year that Iron Man was released: after 2 years of its spin-offs Torchwood and The Sarah Jane Adventures, the series 4 finale 'The Stolen Earth/ Journey's End' brought all three universes together in an incredibly satisfying, organic way to fight Davros and the Daleks.
And then in 2011, Torchwood petered off with Miracle Day, whilst Elisabeth Sladen's untimely passing put an end to The Sarah Jane Adventures. Thus ended an extended universe that still had so much potential, both shows cut off in their prime.
The Doctor Who universe hosts a huge array of beloved characters, or brand-new ones could easily be introduced to audiences. There's so much that potential spin-offs could explore; literally all of time and space.